A citizen of Kosovo has pleaded guilty to hacking the personal data of hundreds of U.S. service members and officials on behalf of the Islamic State (IS) group.

At a June 15 plea hearing in federal court in Alexandria, Virginia, Ardit Ferizi pleaded guilty to providing material support to the IS group and unauthorized access to a computer, the U.S. Justice Department said.

Prosecutors say the 20-year-old man hacked the records of a private company and provided names, e-mail passwords, and phone numbers of more than 1,300 service members and federal employees to IS militants last year.

IS then published the data on Twitter with a warning it would "strike at your necks in your own lands."

Ferizi was arrested in Malaysia in October and brought to the United States in January.